DNA methylation and heterochromatinization in the male-specific region of the primitive Y chromosome of papaya
DNA methylation and heterochromatinization in the male-specific region of the primitive Y chromosome of papaya
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DOI：
10.1101/gr.078808.108
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发表时间：
2008-12-01
期刊：
影响因子：
7
通讯作者：
Jiang, Jiming
中科院分区：
文献类型：
--
作者：
Zhang, Wenli;Wang, Xiue;Jiang, Jiming
性染色体由常染色体进化而来。性别决定区的重组抑制和有害突变的积累导致许多具有异形 X/Y 染色体的物种中 Y 染色体的退化。然而，重组抑制域如何从性别决定位点扩展到整个 Y 染色体仍然难以捉摸。木瓜 (Carica papaya) 的 Y 染色体在大约 2-3 百万年前与 X 染色体分离，代表了最近出现的 Y 染色体之一。在这里，我们报告 Y 染色体的男性特异性区域 (MSY) 的跨度与木瓜 Y 染色体的 13% 相似。有趣的是，Y 染色体的着丝粒嵌入 MSY 中。 MSY 内的着丝粒结构域积累的 DNA 明显多于相应的 X 染色体结构域，这导致染色体配对异常。我们观察到了 MSY 特有的四种旋钮状异染色质结构。荧光原位杂交和免疫荧光分析表明，与相应 X 染色体结构域中的序列相比，与异染色质旋钮相关的 DNA 序列高度分歧且高度甲基化。这些结果表明DNA甲基化和异染色质化在性染色体进化的早期阶段发挥着重要作用。
Sex chromosomes evolved from autosomes. Recombination suppression in the sex-determining region and accumulation of deleterious mutations lead to degeneration of the Y chromosomes in many species with heteromorphic X/Y chromosomes. However, how the recombination suppressed domain expands from the sex-determining locus to the entire Y chromosome remains elusive. The Y chromosome of papaya ( Carica papaya) diverged from the X chromosome approximately 2-3 million years ago and represents one of the most recently emerged Y chromosomes. Here, we report that the male-specific region of the Y chromosome ( MSY) spans similar to 13% of the papaya Y chromosome. Interestingly, the centromere of the Y chromosome is embedded in the MSY. The centromeric domain within the MSY has accumulated significantly more DNA than the corresponding X chromosomal domain, which leads to abnormal chromosome pairing. We observed four knob-like heterochromatin structures specific to the MSY. Fluorescence in situ hybridization and immunofluorescence assay revealed that the DNA sequences associated with the heterochromatic knobs are highly divergent and heavily methylated compared with the sequences in the corresponding X chromosomal domains. These results suggest that DNA methylation and heterochromatinization play an important role in the early stage of sex chromosome evolution.